Vapor heating system with differential loops



Febo 9 fl926.

5. D. HOFFMAN VAPOR HEATING SYSTEM WITH DIFFERENTIAL LOOPS fizzy/n20 yell W 22 Original Filed July 9 1918 5 Sheets-Sheet 1 fiw 29' Feb. 9 1926.

G. D. HOFFMAN VAPOR HEATING SYSTEM WITH DIFFERENTIAL LOOPS Original Filed July 9, 1918 5 Sheets-Sheet 2 WHHHH IHHHHIJHI I I Feb. 9, 1926.

G. D. HOFFMAN VAPOR HEATING SYSTEM WITH DIFFERENTIAL LOOPS Original Filed July 9, 1918 5 Sheets-Sheet 5 naav.

4 ll'tl {J F. I I M T M M a W a Q F 1 7 5 w f z 4 w i 2 .:L ,A W J F 7 4 Feb. Q 9 31926,

G.D.HOFFMAN VAPOR HEATING SYSTEM WITH DIFFERENTIAL LOOPS 5 Sheets-Sheet 4 .lllllllllllillllllll ll Original Fil J ly 9, 1918 Feb, 9 1926c 1,572,482 ca. D. HOFFMAN VAPOR HEATING SYSTEM WITH DIFFERENTIAL LOOPS Original Filed July 9, 1918 5 Sheets-Sheet 5 PW W Patented Feb. 9, 1926.

iononen ntnorrnemor flattens, oagm-nbi N-iliassrenon moinonrmnusrncxatrrz "COMPANY; crwunnauny, ooimnorrcm, A oonronurron or rumors.

' as vapor heating systems, the principal var-ion; WITH nrrrnnmvrmn-Looge i App licatioii maj riifi"afieis; names; ""Ren ev ied se tem ereag i925."

To all aafi mlit 'magj cb ncriiij I ,Bejit known thatI, Gnome-D. HOFFMAN,

a citizen of, the'United States, residing at Pasadena, 'inthe county of] "Los' "Angeles" and State of Gali'for nia,haveinvented new and useful Inn'ovements in Vapor "Heating Systems \vith'Differential Loops, of-vv'hich the fouqwing a specification;

This inve tron relates steam heating systems, knowmin'the trade tingulshing characteristic of whichisthat the workingsteam pressure is very ldw, be I 'ing measured in ounces instead offpounds per square lnch. Such systems include, n

addition to the boiler and :i diators, a steam line for delivering steam 'to the radiators,

and a return'line for conducting water of condensationback to the boiler and for conducting to a radiator. In order that it may perform thesefunctions, 'a part oi the return line, called 'the dry return line is located above the height to which thevnormal boiler'pressure will raise water,'in a nearly horizontal arrangement, but -with a sufficient pitch downward towardtheboil'er;

' and the terminal partofthe return line is conducted to the boiler belowgthe water level therein. Thedry return line is normally open to the atmosphere through an'automatie thermostatically controlledvent,preferably and usually located near the boiler.

\Vhen steam pressure is generated in the boiler, water rises in the terminal partfof the return line to a height abovetheboiler water level -s'ufiicient to balance such res sure; "such rise] ofwat'er beingja proxi- 1 return linej includes a relatively great'l th of nearly horizontal piping Withayertical i terminal seetionyand it is located as'high as feasible abovei the water'level inth'eboilermately'one and'three-fourths' inches or'each vounce of steam' pressure. Usually the'dry [in order that under ordinary pressure the eater will not forcedba'ckfi nto' tlie line in sufficient quantities to uncover 'surfaces of the boiler which are eXposed' to "the direct heat ofthe fire, "since, iftheseg laces should be ncovered," the boiler might" t somaa giiappeng-in h opmepa of low, pressure dis- dint of discharge i tq t s he i ed by steamfrom he "such systems that the boiler pressure permitted, accidentally or otherwise, to mount above the normal working pressure. "For example, a system may be designed to 0p "crate under a normalworking pressure' 'of eight ounces and a max'imumnnbalanced pressure of ten ounces per square inch. Then, if the dry return line is placedvmore than "seventeen and one-half inches above the boiler 'water level, it will remain clear of'water so long as the boiler pressure ,does not exceed the prescribed maximum.

per square inch is easily obtainable by making'toohot a fire, and it is generally in possible to place the lowest horizontal'runs ofthe dry return'line at the height above But'a boiler pressure of several-pounds the boiler water level to which a pressure of even a few pounds'will raise a water column.

The purpose of my invention is to make itimpossible for water to back up from the boiler into the return line or radiators of a vapor'heating' system, though the boiler pressure be raised to no matter how high a degree above the" normal Working pressure, and though the horizontal dry return line he no higher above the boiler water level than the height of a water column which balances a predetermined maximum "Working pressure; and at the same .time to accomplish the following" additional results: I

(1)"To enable a variable operative ressure difference between the steam an returnlines of thesystem to cause circulation, of steam when the boiler pressure is lower than acertain predetermined value.

To maintain a substantially constant pressure difi'erentialbetweeuthe steam and return" lines when .the' boiler pressure exceeds apredetermined amount, and thereby cause circulation of steam in a manner similar-"to that occurring 'when atmospheric pressure is maintained in the return)line "and a pressureis gene'ratedin the: steam line equal to such pressure"differential) v (3) T retain the steam'-in*the"system and prevent loss thereof to" the atmosphere no matter hovvhigh the pressure may "mount. (4) To retain water in th'e 'boiler and prevent it'blowing tune *the atmosphere when the boilersteam pressure is'excessive; (5)'"To permitrele'ase of air from'the return line, even during the continuation of high pressure conditions;

(6) To enable a radiator which was )reviously shut off and has been turned on ur ing the continuation of these high ressure conditions, to become heated quic (1y and conltinue functioning in its normal way; all; Y

(7) To restore the previous conditions and open the return line to the asmosphere as soon as the boiler pressure has diminished to th prescribedmaximum differential.

I have accomplished these objects and results by combining with a vapor heating system and a thermostatically controlled vent therein, a device which I call a difl'erential loop in the manner which I will now describe in detail.

The invention consists in this combination and equivalents thereof as well as in subordinate characteristics, all as hereinafter described and pointed out in the claims.

In the drawings forming part of this specification Figure 1 is an elevation, partly broken away, 'of one form of differential loop embodying my invention which I have applied to the heating system for the purposes above mentioned.

Figure 2 is a longitudinal section of the upper part of said loop on an enlarged scale. 4

Figures 3 and 4 are views similar to Figures '1 and 2, respectively, of another form of he loop. I

Figures 5 and 6 are sectional views showing a third form and illustrating further its conditions and mode of operation under normal pressure and excess pressure, respectively.

Figures 7 and 8 are views similar to Figures 5 and 6 of a fourth form of the invention;

Figure 9 is a diagram illustrating the invention applied in a two pipe heating system. Like reference characters designate like parts in the various figures.

Referring first to Figure 9 for explanation of the entire system, 11 represents 'a heater which may be considered as having the characteristic elements of a steam boiler, and from the steam space of which a rising pipe 12 leads. This pipeis connected to the steam line or main 13, which isa pipe of suflicient capacity to supply steam to all the radiators of the system, and is substantially horizontal, but preferabl slightly pitched downward away from tie boiler. l4, l5, l6 and'i7 represent radiators which are supplied lzy steam connections 18 leading from the steam main 13 and control ed byvalves.

19. The water condensed in the radiators,

together with any air which may have accumulated therein from any cause, flows through outlet valves 20 and the several return connections 21 to the dry return line 22. This return line is located above the level of the water surface in the boiler a distance sufliciently greater than the height to which the maxlmum unbalanced pressure will force a column of water; and is substantially horizontal but is slightly pitched downward toward the boiler to cause a suflicientlv rapid return flow of water; and it is joined to the boiler by a rising or substantially upright or vertical pipe 23, the latter being the vertical end of the dry return line leading into the lower part of the boiler below the water level therein. 24 represents a vent valve in the return line which is normally open to the atmosphere but is adapted to be closed by a float or by a thermostatic motor when the return line is either flooded with water or is filled with steam.

The differential loop is shown at 25 in Figure 9. It is provided withan inlet 26 which is connected with the boiler so as to be affected by the pressure therein, by an .upright pipe 27 leading from the steam main, and a lateral connection 28, or by any other suitable connection; and is further provided with an outlet 29 connected through a pipe '30 with the upright pipe 23 of the return line. Thus the outlet of the loop is in close connection with the thermostatic valve 24 controlling the vent of the return line. There is an extension 31 of the upright pipe 27 below the connection 28, which is provided for entrapping sedi- -ment.

In the arrangement shown the loop' is thus connected to the steam and return lines at a point near the boiler, and in some cases this is the preferable location; but under other conditions it may, and sometimes should, be located at the remote ends of the steam and return lines. Also, in the arrangement shown, the remote end of the steam line is connected with the return line so as to permit return of the water condensed in the steam line, steam being prevented from flowing directly into the return line by a thermostatic'valve 32 which may be of the same type as the radiator return line valves 20. However, instead of connecting the lines as last described, it is within my contemplation to provide a separate return connection from the remote end of the steam 'line to the pipe 27. Preferably the connections between the loop and the boiler should be of such, length and so arranged as to maintain an adequate volume of water in the loopby delivering condensed steam thereto. -The present drawings show an arrangement suitable for this purpose.

The form. of differential loop shown in Figures 1 and 2 comprisesa shell or casing made of'an upper part or casting 25 into which the inlet and outlet open, and a lower part 25 joined by a screw-thread to'the we itfl 'f', re ucer' 33in Whichthe're isjjakphig 34" when is' readily rejmoveble iferi" the" purpose" (if partition [35 which v,di'vidsithe interior "015;; the shell linto" tit e che'mbe sf 36 :37, the v forme aving cepaei-ty fer swi g a, large me (if W er, and 'Kthe e ter p' ki iigf tapped; ho'les fin oin'e" of which is screwed th'ef.

upper 5 end of: It pipe i 38, "which "I ca'll'lli h bgh eing jpip'e, and the other of whi h;

isscrewed e pip'ee'e which I} callth eq lali'zif ing j pip The latter ji-i'ses abpve the atti: tion to such "height ebdve'. the ,lowelfi edge of the outlet that itsforificeis gibqye' the surfaceef .thefwateii which eelleets 'iIi, the

. loopzj That} art of; f-the equalizing pipe which rise above the 'pei'titien is' designhted 40F and is called, forxthepurpose 10f this specification, the equalizing .pipe'extension;

This extension is not a prime 'e'ssehtiel o f-u the invention; but is iseful as a means iditg giving free course to the flow of fstear'n';

through the loop. The termethus applliedl td the pipes and othercelements 'ofjthe dif 1 ferential 100p are descriptive and have no= drawings; .i Water'vof eende he m et ce wtienx 9',

wa e ac im ite tlegea p ewtheze limiting significance, but. include" an el'e ments or devices having the essential'ch-arac l teristics a s 'td function arid resu1t,;ef the arts .here shown and 'descfibedJ-"Ih the owejr "end of the equalizihg pipefisflanju wardly extending slot 41 wh ch forms "a,

cut through either orbothfwalls' offthe' pipe". and it is preferably 'sddesigned-th'at it may; out by, a "metal cutting saw. 7 Any other formfif'restricted orifiee haw GSSefitifiil v the sam'emode of actipn, present y dese l ibe by, whatever means made is, hbwevef, {within the scope of the" proteetion iivhich I clai'mf for! this: part of the device.

pm i-p hea l j p es-111g, n -Ei SJIOWQ I i fi' e 1n enygs mn m w llib lvw he up er. l nd h s t -.'lh l upp r n .,-:t e

b l nc i hP e-prieif ly i in the er ia t tio 5 l-il n imy ei bi l bwf he; out an o he 991111 a 1 1 1 w ll i p @1 he be 'e bn ff he nv n tieh he; this far d cf 'ibed ,befbr'e describ' hei'eb hr Q ti l si i1 1f $t r d n v ht 11,i fi 1' ith x wp ba cing pip a d: equa izm he c amber i ,4 viewed lippe i hambeif itmsthe, second glegtqf n uprigh u 'be 0 71-510 0?z-be we na heaste m ni l f ze ,v etu n l n w h. is se led h w t yandi new ichwh g ea es m me; m ght the,

M79 n the g a ot exceed the 'd isfsfo'depreesedifieyvai'y more or less a cergd g ase; f r example, lth'ef pres' l' ie" difference I betWeeIi-theis'team ehd ieturnilines 10f the Q system is-flimit df o ten,:ouiiees,* the veitieall height between :uhe bottom ofthe' time;

pipewtndthetop-oftheslom in the loop? p i fei hfa 'q idil 'i iis qua 9 abbl t; 71/2 i eh exh zapp x m e igh o he: w'ater cbluinh which; 'th'ebeilingtempera I;

tune, b tiice pres h. i re i-te s mcee#Ev dently however, {this "jvert eal, di tance mjey 1 sing ipew353; ami rehanlber.

less jthamfteri;

and that the "boiler me i ainsz a c l m if; "were.

the ivzitei"*level f textile heightfto whichiwaterg hee,

(i -vertical end23 of the re-tiimtent end n :beh 'es'sure i ac at diinltdiih this, line; This mt-reac es it mmedie .i ,Y tg h e e m hereby; we eje is am pkeie m spher ii lip er i thex b li'nllm ;'bre ifingwater n??? b ih f r eil-ontgq the oilerintqth etk m e e e+hnd $11h a k Pre ir t ui t 1 p ate fat pr p t al tath ampun'ty mir iid l y efi he i, ht'qllg the. w e t- V VI so raised to within ten ouncesof the boiler pr'essurefdr, in general terms, to a'n'l amount equal to'ithe difierence between the boiler pressure and the pressure' equivalent of the water column in'thef water from the "chamber '36 and balancing pipe 88 flows S and return line pressures, due to the water in the loop which must be raised as a column of a certain height before steam can pass, and which stops flow {of steam when the existing diflerential is within the prescribed maximum. -The equalizing pipe 39' is, in effect, a by-p'ass'between that leg (chamber 37-) of the loop which is in steam connection with the boiler and the return line connection of the loop, leading from such a low point in the leg specified that a difference between the water levels in the two legs equal to the. head equivalent tothe prescribed differential must be obtained before steam can pass through it. \Vhen thev boiler pressure exceeds the prescribed difi'erential, this, b -pass permits steam to blow over from it e boiler-to'the return line, without emptying the loop of water,

in whatever amount is necessary to equalize such pressure excess. Equalization 1n the return line of' the excess boiler pressure then takes place through the compression of air entrappedin the return line by the flow of steam into that line after closing of the thermostatic vent. -The pressure in the re turn line-is exerted on the head of the water, column: in thesleg formed by the "chamber 36 and .pipe,3 8,zand tends, together with the weight of that column, to raisethe water levelin the leg formedby chamber 3Zfiand thereby seal the, bypass while tendency f of excess boiler pressure islalways to depress the water in leg 37'and uncover the by-pa'ss.

I have found that, in the operation of 'the device, these tendencies quickly reach a condition of approximate equilibrium in whichv just enough steam =j is allowedlto pass through the equalizingpipe to equalfthe excess pressure in the boiler and so prevent water leaving the boiler and flooding the return line, but not to reduce the pressure (lifierential, which isalways maintainedat the given value of ten ounces (or whatever it maybe for anyjparticular case). An in crease in the boiler pressure causes more steam to flow through the equalizing pipe in exactly the measure necessary to balance this increase. while decrease of boiler [pres sure allows the entire flowof steam through the equalizingpipe to be cutfofi'. Althoughthe water level in the. chamber may surgeand fluctuate while the boiler pressure is above ten ounces alternately opening and closing the equalizing pipe, such fluctua tions occur so rapidly that the ressure differential vbetween the steam an return "lines remains substantially constant.

'lhusthe system is enabled automatically and instantly to adapt itself to all pressure conditions and return to normal operating conditions after having been under an abnormal pressure, and to do so without noise;

steam flowin from the boiler to force itself into the radiators and to expel-from the latter the water of condensation and any air which may be trappedin them. When the boiler pressure subsides to,. or below,

the prescribed differential, after having risen above it, blowing of steam over into the return line ceases, the thermostatic vent in this line opens, and the system continues to function without interruption in the'normalway. 7

I have found that the'restricted orifice to the eqlualizing pipe provided by .the notch 4.1, w ich makes a graduated :opening according as itis uncovered to a greater or less extentby subsidence of the water in the outer 1e and the storage chamber-of relatively. arge capacity "provided at 36 in.

the upper end of the loop casing, are elements which appearrinpractice to be, if not absolutely essential, at least highly impor tant in securing the results described. The

location of the equalizing pipe at theside of the loop next to the outlet also has an important effect in a loop made substantially asthat here shown, .where the outlet opens from-the side of the casin such effect being to prevent, inrsufiicient y'large measure,

loss of water entrained bythe'steam which flows through the e ualizing pipe-when the loop acts. At suc times asubstantial amount of water is entrained with the flowby lo'ssof the water head which is reli'ed'on tomainta'in the differential. But with the equalizing pipe arranged at theside ot' the casing next ,to the outlet, the water which issues from this pi estrikes the top' wall or upper head oft e easing,ancl';is ba'filed and deflected from the"outlet,'iwhereby the AVAILABLE co y I d fore 43 and (a stdragel chamb rx44- Figur $719 116. :8 v how an arrang h t ba inc P p 38" 10 is wi'thinyhe casing putf leg f and the e'q uqlizl ipg e ,7 9? 13 a radiator is 'turnedon, or in order to cause opening of the vent valvei when the system returns to its normal'lowpressure condition after subsidence/of abnormally high pressure.

It is to be understood, of course, that the particular construct-ions shown, and the terms applied to the parts and elements thereof, are not intended to limit the scope of the protection hereinafter claimed tothose specific constructions. Generically all the forms of differential loop hereinbefore described and all other devices equivalent thereto in purpose, structure, function or result, within the scope of protection herein after claimed, are blow over devices adaptet to permit transfer or blowing over of steam from the steam line to the return line,

when the .boiler pressure exceeds the prescribed differential, andcontaining sealing or closing means adapted to resist such steam flow with a continuous yielding force of {limited maximum value. The sealing means here disclosed is a column of water,

and the force with which it o poses the steam pressure and tends to sea the blow over passageway is the force of gravity, which is limited to the height of the maximum column of water which can exist in the loop, and acts not onl before blowing over of steam begins, but a so while steam is flowing and without interruption after the flow ceases.

The combination with a heating system as,

" and with the effect described, of any device which has these essentials is intended to be protected by my claims,"whatever may be the specific construction of the device and the specific terms which may most aptly describe the parts thereof.

All systems and combinations substantially equivalentto'that here described and pointed out in the following claims are within the scope of my invention and the protection which I claim without limitation y restricted'definitions which may be applied to the terms used. Thus, for instance, the term vapor heating system is intended to include any low pressure steam heating system of the open or vapor type or the closed or so-called vapor vacuum type, wherein a loop may be used in the manner and to the effect set forth. The illustration and description of the mode of connection between thesteam line and the loop are not intended to indicate any limitation as to the point at which such connection may be made with the pressure side of the system, forthe pressure receiving side of the loop may be connected with equally good effect to any partof the steam connections leading from the boiler or even directly to the steam space of the boiler itself. Having now described a specific form of my invention and explained the principles leg into w thereof,but without attempting to describe all the forms in which it may be made or all the possible modes of its use, I declare that what I claim and desire'to secure by Letters Patent is:

'1. A heating'system comprising a'boiler, a heating element, steam and return lines between the boiler and heating element, a blow over device having an inlet'connected to the boiler and an outlet connected to the return line, and containing a sealing medium adapted to op 'ose continuous yielding resistance of limited flow of steam from said inlet to said outlet, and a thermostatically controlled vent valve in communication with the return line and with the outlet side of said device, said thermostatically controlled valve being located in close proximity to said outlet.

2. The combination in a vapor heating system of a boiler, a radiator, steam and return lines between the boiler and radiator, a blow over device connected between the boiler and the return line having. 'means to maintain a given ressure difference, between them while still permitting passage of steam from the steam'liue to the return line when the boiler pressure exceeds the given difference, an air escape vent in the return'line', and a thermostatic valve controlling said vent and adapted to permit escape of air and to prevent escape of steam.

3. A vapor heating system comprising in combination a boiler, a steam line, a return line, a radiator in communication with said lines, and a differential loop embodying two separate chambers one above the other, a connedtiofffrom the .upper chamber, to the return line, a connection from the lower chamber to the boiler, and two pipes assing between the chambers, one of sai pipes having an opening at a height abovethc bottom orifice of the other pipe-arranged in a' plane othenth'an horizontal, whereby it is more or less uncovered by lower or higher levels of .the water in the lower chamber. v

'4. A vapor heating system comprising the combinationof a boiler, a steam line, a return line, a radiator in {connection with both of said lines, a difi'erentialloop having an inlet connected with the boiler and an outlet connected with the return line, said loop includin also water legs" in communication with t e inlet and thefoutlet and an equalizing pipe forming a by-pass from the ich said inlet opens to. the leg into which said outlet opens, the return line having a vent to the atmosphere in close proximity to the outlet'ffrom said loop,

and a thermostaticallycontrolled valve connected tosaid vent and adapted to be closed by the. temperature of live ,steam maximum force}to the when steam flows through said equalizing no pipe to the steam line.

said leg and having an guana:

5. A vapor heating system comprising in combination a boiler, a steam line, a return 'line, a radiating element incommunication with said lines, and a difierentialloop coniprisin a casing. havin a transverse partition dividing the same 10b0 an upper chamber and a depending leg, and having an inlet beloyv said partition connected with-the boiler and an outlet above the artition from the upper part of said cham r connected with said return' line, a balancin pipe fixed in 1 e. p a P A vaporheatingsystem as claimedin claim 5 distinguishedby the fact that the m let in said equalizing pipe is a slot cut through the wall of the pipe upwardly from the lower end thereof.

8. A va r heatin system as claimed in claim 5 distinguishe -by the fact that the balancing piple is nearer that side of the casing into whic the inlet totheloop o ens and the equalizing pipe is nearer that si e of the casin through which the outlet opens.

9. i vapor heating system comprising the combination with a boiler, a steam line, a return line and heat radiating means in communication with said lines, of a water containing loop between said lines and comrising two legs connected togetherat a low evel and connected, at relatively higher levels, one with the boiler and the other with the return line, the connection between the boiler and loop being so arranged that water condensed in such connection is caused to pass through the loop into the return line and so maintain a given maximum height of water in that'leg which is connected to the return line, said loop also comprising a bypass extending from that leg which is connected to the boiler, .bein connected with said leg at a level above t e connection be-. tween the two legs and opening to the return line at a height above the water level in that leg which is connected to the return line.

10. A vapor heatingpystem comprising the combination with a oiler, a steam line, a

return line and heat radiating means in communication with said lines, of a loop loge together at a low. lev. ,and'connocted it higher levels with the rand'the return line,

tively, an equilini by-pass having a re tively low inle'tfin t e leg which is connected to the boiler and a relatively high outlet in the which .is connected to the return line, said inlet being so formed and arranged that it is opened to a greater or less area in proportion to the extent of depression of the surface of the water column in the leg whereto said inlet opens.

11. A vapor heating system comprising,

the combination with a boiler, a steam line,

a return line and heat radiating means in communication with said lines, of a differential loop adapted to maintain a pressure differential between the said lines, and comprising a leg connected to the boiler to receive condensation of, steam and comprising also a second leg connected to the return line at a point such that the water therein is able to overflow to the return line and the maximum height of the water 1e therein is established by such overflow, an

a bypass connection leadin from a relative- 1y low point in that leg w ich is connected to the boiler to a point of dischar e into the return line at a relatively higher evel.

, "12. A vapor heating system comprisin a boiler, a radiator, a steam line connec to conduct steam from the boiler to the radiator, a return line connected to conduct water of condensation from the radiator to the boiler, a differential loop havin an inlet connectedto receive steam from t e boiler and an outlet. connected to the return line, said loop being constructed with water legs connected to one another at their lower ends, the water columns in which legs are exposed at their heads to the pressures existing in said inletand said out et, respectively, and the loop comprisin further a by-pass from a relatively low oval in that water leg which is exposed to the inlet pressure, to

a relatively higher level in that leg which is exposedto the outlet pressure; combined with a vent to the atmosphere from the return line and a thermostatic valve controlling said vent and constructed to be closed bythe heat of live steam and to be opened by cooling to a temperature lower than that of steam,-said vent and valve being in close proximity to the outlet from the loop.

In testimony whereof 'I have aflixed my signature.

GEORGE 1). HOFFMAN. 

